Answer:
He must survey 123 adults.
Step-by-step explanation:
In a sample with a number n of people surveyed with a probability of a success of
, and a confidence level of
, we have the following confidence interval of proportions.
In which
z is the z-score that has a p-value of
.
The margin of error is:

Assume that a recent survey suggests that about 87% of adults have heard of the brand.
This means that 
90% confidence level
So
, z is the value of Z that has a p-value of
, so
.
How many adults must he survey in order to be 90% confident that his estimate is within five percentage points of the true population percentage?
This is n for which M = 0.05. So






Rounding up:
He must survey 123 adults.
Answer:
see explanation
Step-by-step explanation:
Since the 2 figures are similar then the ratios of corresponding sides are equal, that is
=
( cross- multiply )
18x = 48 ( divide both sides by 18 )
x =
=
= 2 
Similarly
=
( cross- multiply )
18y = 30 ( divide both sides by 18 )
y =
=
= 1 
Answer is square root of 39
Answer:
3.5ft
Step-by-step explanation: